working with 1m faces mesh. how to uv map/unwrap?
ok. after the comment of m.ardito i tried uv mapping with easier stuff. after i knew the basics i did my landscape again (using heightmap) with fewer faces. then i could unwrap it and assign my texture to it. after that i didsubdivide smooth a few times to get to an hihger detail grade. 

no need to answer anymore. 

sadly i cant accept my own answer right now. gotta wait 2 days.